The present invention relates to amorphous Nickel alloys for electrical resistor and particularly Ni--Cr--B--Si alloys in amorphous or partially crystalline state which has a relatively high electrical resistivity and a small temperature coefficient of resistivity.
Metallic materials with a relatively high and temperature-independent resistivity are of great interest for the production of high quality resistors. The metallic materials in amorphous state have a relatively high electrical resistivity and a small temperature coefficient of resistivity (hereinafter referred as TCR) and the metallic materials in amorphous state are crystallized through heat treatment.
In order to use an amorphous materials for practical resistors, this amorphous material should have temperature-independent resistivity before and after crystallization, a relatively large change in the resistivity at the crystallization temperature (hereinafter referred as Tcr) and possibly high Tcr (e.g., .about.450.degree. C.).
A nearly zero TCR has been found in the amorphous Ni--B--Si alloys by adjusting metalloid concentration (K. Fukamichi, H. M. Kimura, T. Masumoto; Journal of Applied Physics 52, 2872, 1981).
Unfortunately, in these alloys and other amorphous alloys having extremely small TCR, known in the literature, the temperature dependence of resistivity after crystallization shows generally large positive TCR. Hence, these alloys are not suitable for heat treatment.
The object of this invention is to provide metallic materials in amorphous state which have a relatively high and temperature-independent electrical resistivity in the conventional operating temperature (-50.degree..about.150.degree. C.) of electrical components, i.e., amorphous materials of a very small TCR.
Another object of this invention is to provide a resistance adjustment process through heat treatment (hereinafter called as thermal trimming) of the alloys. So far, the resistance value of the resistor with crystalline materials has been adjusted or trimmed by means of geometrical changing technology, e.g., surface polishing, anodic oxidation or laser beam cutting after they are manufactured with a tolerance value of .+-.5% and separate resistance adjustment for each and every resistor should have been made.